Astronomers Spot Planet Circling Distant Star

Boston Globe

Another planet has been discovered outside the solar system, orbiting a star called Rho Coronae Borealis, which lies about 50 light years (or 295 trillion miles) from the sun. The astronomers who made the find say this lends support to the idea that planets are commonplace throughout space.

While at least eight other planets have been discovered outside the solar system in the last two years, some astronomers question whether they are truly planets. If they instead formed the way stars do, they might have little relevance in estimating how common planets might be.

Stars are believed to form through a gradual collapse of gas toward a central point; planets are thought to form from gas and dust swirling around in a huge disk and gradually coalescing into larger and larger chunks, which in turn collide and stick together to eventually become planets.

Some astronomers, including David Black, director of the Lunar and Planetary Laboratory at the University of Houston, think all the ``planets'' found beyond the solar system may have formed the way stars do, and should be classified as ``brown dwarfs'' -- essentially failed stars, too small to ignite their nuclear fires.

But the team that discovered the latest planet, described in a paper to be published in the Astrophysical Journal Letters, say its orbit clearly indicates that it formed the same way planets in the solar system did. Unlike some of the other planets, which have elliptical (elongated) orbits, this one has an orbit that is nearly a perfect circle. It orbits its star every 40 days, and is about the size of Jupiter.

``This discovery helps show that giant planets like Jupiter may be reasonably common around ordinary stars,'' said Robert Noyes, one of the planet's discoverers.

Co-discoverers were Martin Krockenberger, Sylvain Korzennik, and Peter Nissenson of the Smithsonian Astrophysical Observatory in Cambridge, Mass.; Saurabh Jha, a Harvard University graduate student; Timothy Brown and Edward Kennely of the National Center for Atmospheric Research in Colorado; and Scott Horner of Penn State University.